WESTWOOD, CA - MAY 20: Actress Naya Rivera attends the premiere of Warner Bros. Pictures' "Hangover Part III" at the Westwood Village Theater on May 20, 2013 in Westwood, California. (Photo by David Livingston/Getty Images)

WESTWOOD, CA - MAY 20: Actor Mike Epps (R) and wife Mechelle McCain attend the premiere of Warner Bros. Pictures' "Hangover Part III" at the Westwood Village Theater on May 20, 2013 in Westwood, California. (Photo by David Livingston/Getty Images)

WESTWOOD, CA - MAY 20: Actor Mike Epps (R) and wife Mechelle...

WESTWOOD, CA - MAY 20: TV personality Gloria Govan and NBA player Matt Barnes attend the premiere of Warner Bros. Pictures' "Hangover Part 3" at Westwood Village Theater on May 20, 2013 in Westwood, California. (Photo by Frazer Harrison/Getty Images)

WESTWOOD, CA - MAY 20: NBA player Metta World Peace (R) and his son attend the premiere of Warner Bros. Pictures' "Hangover Part 3" at Westwood Village Theater on May 20, 2013 in Westwood, California. (Photo by Frazer Harrison/Getty Images)

In its first five minutes, “The Hangover Part III” delivers a sight gag involving a giraffe that's exactly what people will want from this movie — something extreme and outrageous, a little bit mean and a whole lot funny. It is the last big laugh in the entire picture.

Director Todd Phillips and his co-screenwriter Craig Mazin have taken what should have been a hysterical comedy and have turned it into an unpleasant action drama, albeit one performed in a lighthearted, semi-comic way. It's the worst possible blending of genres: Everything is too ugly for a laugh and too dumb to be taken seriously.

Some good features remain as a kind of echo. Phillips is an economical director who knows when to cut and what to skip, and Zach Galifianakis is completely abandoned and invested in his role as Alan, a self-centered and mentally skewed 40-year-old man who still lives with his parents.

The movie starts promisingly enough. Alan has gone off the rails, and his friends and family stage an intervention. Actually, even this is a little odd, in that Alan doesn't have a drug or alcohol problem — he's just crazy — but that's OK. Anything to get him on a two-day road trip with his three friends (Bradley Cooper, Ed Helms and Justin Bartha) heading to a mental health facility in Arizona.

They're going to get into trouble. We know this. But what we want is for them to find trouble because they make a mistake or give into temptation. Instead, 15 minutes into the movie — prepare to be amazed — they are run off the road by a truck and taken prisoner by a mobster. The mobster is played by John Goodman, who is directed as if he were in a Scorsese movie. He takes one of them (Bartha) hostage and tells the other three that their friend will be killed unless they kidnap and bring back a rival mobster, Mr. Chow (Ken Jeong). That's the movie.

Can you tell why this can't work? The situation is disturbing. The men stand to gain nothing but must risk their lives just to maintain the status quo. The real contest is between the mobsters, with the protagonists just bystanders in their own movie. Not only should this screenplay never have been filmed, it never should have been completed.